555 astable driver to use as a twinkler

[konky]

For the life of me I cannot find a circuit design to use as a twinkler effect to operate a 15 watt x 12 volt LED. Can someone assist me?

 

[D.A.(Tony)Stewart]

can you sketch a waveform in current vs time of the twinkle effect and post it?

 

[konky]

Here is what I know; 30 to 50 hz freq. I think about 98% on with 2% off creates the twinkle effect. I have no waveform to post. Thanks

 

[D.A.(Tony)Stewart]

You can breadboard some Schmitt trigger oscillators using CMOS gates or 555 timers. But the best effects are pre-programmed sequences in an embedded uC sold with outside xmas lights.
**broken link removed**

 

[konky]

That would not give the "twinkle" effect. It gives a sequential effect. By twinkle I mean about 98%on and about 2% off(like a distant star).
Thanks

 

[response123]

**broken link removed**
The above given link may be helpful of what you are looking for. Best of luck

 

[jpsganesh]

**broken link removed**
The above given link may be helpful of what you are looking for. Best of luck

every time whenever u power it on u need to select mode 7 to get twinkle effect. by default Random mode will give light effect of all modes.


for 555 Astable time calculator

http://www.ohmslawcalculator.com/555_astable.php

try with low freq. 30 or 50 Hz twinkling will be very high speed. try with less than 10Hz. It'll be good.

 

[konky]

Thanks!
Questions:
Is driving it with 12 to 14 VDC ok?

How do I select mode 7 ?

 

[ark5230]

98:02 This ratio at 30 - 50 Hz is very difficult to perceive. I think there is something missing or wage. Twinkling like stars may need different combination !!!

 

[konky]

Huh!!! I not understand that.

 

[ark5230]

Here is what I know; 30 to 50 hz freq. I think about 98% on with 2% off creates the twinkle effect. I have no waveform to post. Thanks

You need 30 - 50 Hz with 98% ON time and 2%OFF time.
Can this type of effect be perceived by normal human is the question.
This means that can one see this as twinkling?? It would look continuously glowing.

 

[jpsganesh]

If you are familiar with micro controller use some small/basic uC like PIC10 series or PIC12 series. You can create random pulse at different freq which will give very good twinkle effect. This will give good look and attractive. u can re-prog it whenever u want to change the pattern.